Internet telephony has succeeded in overcoming its initial barriers of low quality, non-ubiquitous hardware, and lack of interconnection. Today, Internet telephony is approaching wireline voice quality. Because use of the Internet significantly lowers costs in almost every aspect of telecommunications compared to a conventional telephone network (e.g., transmission costs, switching costs, etc.), the Internet has driven many conventional telephone operators out of business.
Many people predict IP-based mobile solutions, such as mobile IP (MIP), will have the same kind of impact on cellular operators because the current wireless networks, like their telephony counterparts, share many characteristics: complex architectures, highly inefficient bandwidth utilization, and high transport cost. Like their telephony counterparts, cellular networks cannot compare with the bandwidth and the cost efficiency offered by the Internet solutions. For example, it has been argued, a wireless fidelity (WiFi™) network, has a per-user capacity 10 to 50 times higher than that of a cellular network, but with less than 1% of the infrastructure cost. Studies have shown that WiFi's physical layer can support mobile users traveling at a speed of 60 to 80 Km/sec. Therefore, WiFi networks can potentially provide the services that are offered by current cellular operators at a significantly lower cost.
However this prediction has failed to materialize. WiFi routers have a limited transmission range (e.g., a few hundred meters in an outdoor area). This means that a handoff is triggered every 5 to 10 seconds in a WiFi-based wireless network. IP-based mobile solutions cannot seamlessly support this kind of handoffs. Some architectures have been proposed to reduce the handoff frequency. One example architecture segments a WiFi network into several domains and each domain has a gateway router for handling handoffs between domains. If a mobile node (MN) moves within a limited area, handoffs within a domain only trigger signaling messages exchanged among the routers inside the domain. However, many issues, such as security and packet loss during handoffs, are still not addressed with these architectures, and it is doubtful that they can support the kind of mobility provided by cellular networks. Another drawback with many IP-based approaches is that they do not address the data encryption issue after handoffs. The handing of encryption keys is a time consuming process in conventional wireless networks.
Thus, there is a need for a novel IP based wireless communication network architecture that can seamlessly support a device's zooming in a WiFi network and harvest the low-cost, abundant bandwidth of a WiFi network.